Apparatus and method of constructing marine float structures

ABSTRACT

Apparatus and a method of constructing a marine float structure, such as a large-sized ship structure, is accomplished by assembling a number of divided ship portions on a ship building base. The first divided portion is transported on the water surface by means of a composite pontoon which is so constructed that each individual portion thereof can be separated from the other up and down or forwardly and backwardly. Then the composite pontoon is caused to sink down in the water so that said first divided portion of the ship can float of its own accord on the water surface. Subsequently the second divided portion of the ship is transported on the water surface using the same pontoon as mentioned above. A part of the composite pontoon is separated from the remaining body and allowed to sink down in the water while said second divided portion of the ship is held by the remaining portion of the pontoon. The separated part of the pontoon is used to float said first divided portion of the ship on the water surface, thereby combining both divided portions of the ship in a single unit on the water surface.

United States Patent 91 Takezawa et al.

[ APPARATUS AND METHOD OF CONSTRUCTING MARINE FLOAT STRUCTURES [75]Inventors: Isoe Takezawa; Masataro Muto;

Koichi Hori, all of Nagasaki City, Japan [73] Assignee: MitsubishiJukogyo Kabushiki Kaisha, Tokyo, Japan [22] Filed: July 6, 1972 [21]Appl. No.: 269,318

Related US. Application Data [63] Continuation-in-part of Ser. No.40,520, May 26,

[52] US. Cl. 114/77 A, 114/65 R, 114/77 R [51] Int. Cl B63b 3/02 [58]Field of Search 114/77 R, 77 A, 65 R,

114/65 A, 44, 45, 46, 49, 15 F, 66.5 F; 6.1/64-68; 9/8 R [56] ReferencesCited UNITED STATES PATENTS 3,680,512 8/1972 Yamura 114/46 3,011,25212/1961 Svensson 114/65 R 3,464,212 9/1969 Yamagata et al.-.... 61/652,732,818 1/1956 Quirin 114/77 R 2,728,319 12/1955 Engstrand 114/77 R2,480,144 8/1949 Laycock 114/49 2,518,091 8/1950 Stopkevyc ll4/.5 F

FOREIGN PATENTS OR APPLICATIONS 97,144 11/1960' Norway 1l4/65R Oct. 16,1973 Primary Examiner-Milton Buchler Assistant Examiner-E. R. KazenskeAttorney0tto John Munz [57] ABSTRACT Apparatus and a method ofconstructing a marine float structure, such as a large-sized shipstructure, is accomplished by assembling a number of divided shipportions on a ship building base. The first divided portion istransported on the water surface by means of a composite pontoon whichis so constructed that each individual portion thereof can be separatedfrom the other up and down or forwardly and backwardly. Then thecomposite pontoon is caused to sink down in the water so that said firstdivided portion of the ship can float of its own accord on the watersurface. Subsequently the second divided portion of the ship istransported on the water surface using the same pontoon as mentionedabove. A part of the composite pontoon is separated from the remainingbody and allowed to sink down in the water while said second dividedportion of the ship is held by the remaining portion of the pontoon. Theseparated part of the pontoon is used to float said first dividedportion of the ship on the water surface, thereby combining both dividedportions of the ship in a single unit on the water surface.

3 Claims, 11 Drawing Figures I PATENTEDUEI 181973 3.765.359

: P f I L.W.L

1 APPARATUS AND METHOD OF CONSTRUCTING MARINE FLOAT STRUCTURESCROSS-REFERENCE TO RELATED APPLICATION This application is acontinuation-in-part of US. application Ser. No. 40,520, filed May 26,1970 by the same applicants and now to issue as US. Pat. No. 3,675,606on July 11, 1972.

BACKGROUND OF THE INVENTION The present invention relates toapparatusand a method of ship building apparatus and more particularly a methodof constructing a large-sized ship structure such as a marine vessel byutilizing economical equipment that does not use an inclined shipbuilding base or a dock.

In recent years there is a trend of building marine vessels, ships inlarge sizes. There are a number of tech nical problems with using aninclined ship building base to construct large-sized marine vessels anda ship constructing dock is generally used instead of a ship buildingbase.

However, enormous expense and considerable time are required in erectinga ship constructing clock. In some instances it is substantiallyimpossible to construct such a large-scale dock by virtue of thegeographic conditions of a shipyard.

In view of the above conditions, it has heretofore been proposed as analternative procedure in ship building to carry out the launching of aship by the use of an inclined carriage or using pontoons. In the caseof the inclined procedure a sliding surface or rollingsurface isrequired to slide the hull onto the water surface. Further, the cast ofthis type of equipment is high. Further, the inclined carriage is liableto twistduring the descent of the hull.

According to a conventional procedure for constructing a hull on ahorizontal ship building base using a quay and lauching it by means of apontoon, it is unavoidable that such pontoon must be of a great length.Namely, according to this procedure, as shown in FIG. 1, the height h ofthe surface'of the ship building base 01, mounted on a dry-land typefoundation from the water surface (L.W.L.) at low tide should be atleast 4 meters by adding an allowance of water line (draft) about 1 m tothe difference 3 m between the periods of low and high tides.

On the other hand, a'hull S constructed on the ship building base 01 canbe transferred onto the pontoon only by maintaining the uppersurface ofthe pontoon P and the surface of the ship building base 01 at equalheights. Consequently it becomes necessary to have the pontoon P withthe hull mounted thereon exposed at least 4 m above the water surface.For this purpose, the entire height H of the pontoon withthe addition ofdeepness below thedraft lineshould be at least twice as much as theabove-mentioned h, that is, at least about 8 m. Needless to say, thebasis of the calculation has been referred to in the case of using apontoon corresponding to the entire length of the hull S.

As a result, the conventional methods require the pontoon P itself to besufficiently large-sized so that the manufacturing cost becomes veryhigh. Also a largesized hull S that is constructed on a horizontal shipbuilding base is rather difficult to be transferred onto the pontoon Pand is thus an extremely complicated and time consuming operation.

SUMMARY OF THE INVENTION The object of the present invention is toprovide apparatus and a method of manufacturing a large-size shipbuilding base without the above-mentioned disadvantages.

A further object of the present invention is to provide apparatus and amethod of constructing marine float structures, comprising theconstruction of large-sized marine float structures such as large-sizedtankers in a suitable number of separately divided portions on ahorizontal ship building base by utilizing the facilities of a quay andthe use of composite pontoons formed of many upand down or forwardlyand/or backwardly separable portions wherein;

first of all, the first divided portion of the hull is transported ontothe water surface;

then the composite pontoon is caused to sink down in the water to launchsaid first divided portion;

subsequently, the second divided portion is transported onto the watersurface using the same composite pontoon but in this case a portion ofthe composite pontoon is separated therefrom so as to sink down in thewater and said second divided portion is held in condition exposed abovethe water surface by means of the remaining portions of the compositepontoon;

and simultaneously said first divided portion is caused to float asexposed above the water using said separated portion of the pontoon sothat both divided portions can be jointed on the water surface.

A further object of the invention is to provide a pontoon structure inwhich a plurality of hermetically sealed modular pontoons can be easilyassembled in a spaced relationship to one another to achieve a unitarypontoon structure whereby individual modular may communicate with oneanother and to provide a stabilized and balanced inclined position forthe unitary pontoon structure.

A further object of the invention is to provide a molded plasticlongitudinally unitary pontoon structure comprising a plurality ofindividually detachable unit pontoons having extendible connection meansbetween respective adjacent unit pontoons, wherein said extendibleconnection means provide a spaced relationship between adjacentindividual unit pontoons.

Other objects and advantages of the present invention will becomeapparent from the following description with reference to embodiments inthe construction of a large-sized tanker.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view showing anexample of a launch ing procedure using a pontoon of the conventionaltype.

FIGS. 2 through 7 are views showing a constructing of a marine floatstructure according to first embodi ment of the present invention. FIG.2 is a perspective view of a composite pontoon.

FIG. 3 is a side view of a hull which is constructed in divided form.

FIG. 4 through 7 are side views showing examples of construction steps.

FIGS. 8 through 10 show a second embodiment of the present invention.FIG. 8 is a perspective view of another composite pontoon.

FIG. 9 and 10 are side views showing examples of construction steps.

FIG. 11 shows a third embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION With reference to FIGS. 2 through7 showing a first embodiment of the present invention, B indicated analmost horizontal ship building base constructed by utilizing a quay,and the hull S is to be constructed thereon in the form of a number ofdivided portions in the direction of fore and aft parts of the ship.

The height of the ship building base B is determined in such a mannerthat the upper surface of the base B cannot be immersed in the water athigh tide or by the high waves.

As an example, assume the difference in tidal position to be 3 m at lowand high tides and adding the allowance draft line thereto, the height hof the ship building base B from the water surface at low tide will becomputed to be about 4 m.

The character P indicated the composite pontoon for use in thisembodiment and said pontoon P consists of two pontoons P and P which areoverlapped in the manner of bieng separated from each other. These unitpontoons P and P are partitioned inside in the form of a plurality ofareas to constitute a number of float chambers l and 2.

These float chambers 1 and 2 are adapted to communicate with respectivepipes for pouring and discharging water (not shown in the drawings), sothat it is possible to adjust the buoyancy and trimming of each pontoonby pouring water into, or discharging it from, each float chamber. It isto be noted that the abovementioned water pouring and dischargingapparatus is of conventional construction. The size of the compositepontoon P is such that its length L is about one half of the length of avessel to be constructed. Its depth H is about two times the abovementioned height h, namely about 8 m, in order that the upper surface ofthe com posite pontoon may be held in level with the surface of the shipbuilding base B even when tidal position is the lowest and the head dropbetween the water surface and the surface of the ship buildling base Bamounts to a maximum (about 4 m).

When a tanker is constructed using the abovementioned composite pontoonP and the horizontal ship building base, the hull S is constructed inthe ship building base B. For example, the hull S may be in the form offour divided parts such as the fore part F, for half part tank TF, afthalf part tank TA and aft part A, as shown in FIG. 3.

Subsequently, the composite pontoon P is brought forwardly of the shipbuilding base B and then ballast water is poured into, and dischargedfrom float chamber 1 and 2 in a suitable manner so that the uppersurface of the composite pontoon P is adjusted to assume the same heightas the surface of the ship building base.

After this operation has been accomplished, the fore part F and the forehalf part tank TF are transferred onto the above-mentioned pontoon P.

For this purpose, a transfer carriage is used though it is notillustrated in the drawing.

Along with the progress of this transfer mounting, gravitation acting onthe composite pontoon is gradually increased so that it is necessary todischarge the ballast water from each flaot chamber 2, in order tomaintain the draft and trimming of the composite pontoon P. In certaininstances, as shown by the imaginary line, there is provided a base seat3 at the bottom of the water beforehand and then the composite pontoon Pis brought into contact with the base seat 3 to make use of astabilizing operation effectively.

In this way, when the fore part F and the fore half part tank TF havebeen mounted on the composite pontoon by transfer, they are jointed bywelding or the like thereon to complete the fore part SF of the hull.The fore part F and the fore half part tank TF are jointed after theyhave been mounted on the composite pontoon to facilitate their mountingon the composite pontoon P. If necessary, both may be jointed on theship building base B beforehand and it is also possible to constructthem in a body from the beginning without preparing them in dividedform.

As mentioned above, in the event that the fore part F and the fore halfpart tank TF are mounted on the composite pontoon by transfer and arejointed together to complete the fore ship portion SF, the combined unitis transported onto the water surface by means of a towboat or the likewhile mounting it on the pontoon. Then ballast water is poured into eachfloat chamber 1 and 2 of the pontoon in a suitable position so that itcan sink down and the fore ship portion SF only can float of its ownaccord on the water surface.

Subsequently, as shown in FIG. 5, the aft half part tank TA and the aftpart A are mounted on the pontoon by transfer in exactly the same mannerusing the same pontoon as mentioned above and they are jointed togetherto complete the aft ship portion SA, which is then transported onto thewater surface by means of a towboat or the like.

Thereafter, as shown in FIG. 6, ballast is suitably poured into eachfloat chamber 2 of the lower half unit pontoon P constituting thecomposite pontoon so that only the unit pontoon P is caused to sink downin the water and be separated from the other unit pontoon P As a result,the aft ship portion SA is destined to be supported by the buoyancy ofthe unit pontoon P Then only but the whole body is allowed to remain asexposed above the water surface except that the height from the watersurface is reduced.

Consequently, the separated unit pontoon 2 is brought right below thefore ship portion SF by means of a towboat or the like. Then the ballastwater in each float chamber 2 is suitably discharged therefrom until thefore ship portion SF is allowed to float and be exposed above the watersurface.

Then, as shown in FIG. 7, both ship portions are drawn together andtheir corresponding joint portions are caused to engage each other sothat both portions are jointed on the water surface to complete the hullS.

As mentioned above, it is necessary that a pontoon of great depth beused to compensate for the head drop h between the water surface and thesurface of the ship building base when the fore ship portion SF and theaft ship portion SA are mounted on the pontoon by transfer asexemplified in this embodiment. But, once both ship portions SF and SAare transported onto the water surface for the purpose of jointing themon the water surface, it is no longer necessary to use the abovementioned pontoon of great depth. So, attention is drawn to the factthat it is possible to achieve the same purpose sufficiently by usingthe pontoon of about half of the above mentioned depth. For thispurpose, to begin with, when the fore ship portion SF and the aft shipportion SA are transferred from the ship building base onto the watersurface, the unit pontoons P and P are overlapped to increase the depthof this assembly to achieve the required purpose. Thereafter bothpontoons are separated from each other so that the fore ship portion SFand the aft ship portion SA can float and be exposed above the watersurface for achieving their joint effect.

Now, a second embodiment of the present invention will be explained indetail with reference to FIGS. 8 through 10.

In this embodiment, as an example, the composite pontoon P consists offive unit pontoons P P, which can be divided forwardly and backwardly asshown in FIG. 8.

The size of this composite pontoon is illustrated to show that itslength L is about one half of the ships length. Its depth H shows thatit is about twice the height h between the surface of the ship buildingbase B and the water surface at low tide. This is accomplished in thesame manner as the aforesaid embodiment, which has already beendescribed in detail.

Though not shown in the drawing, there are provided a plurality ofpartitioned float chambers in all the respective unit pontoons P, P inthe same manner as the afore-explained embodiment. Therefore, it ispossible also to adjust buoyancy and trimming by suitably pouring Waterinto, or discharging it from each float chamber. Also it is possible toprovide means for communicating a float chamber with another ashereinafter described.

In order that a ship be constructed using the above mentioned pontoon P,as described in the afore-said embodiment, the hull is constructed individed form on the ship building base B. Then, as shown in FIG. 9, thefore ship portion SF is transferred onto the water surface. The ballastwater is uniformly poured into the floatchamber of each unit pontoon P Pto cause the pontoon P to sink down in order to permit the floating ofthe fore ship portion SF of its own accord on the water surface. Thus,the same composite pontoon is used again to transport the aft shipportion SA onto the water surface. Under these conditions, as shown inFIG. 10, ballast water is poured intothe float chamber of each unitpontoon P P and P respectively and these unit pontoons are separatedfrom the other unit ones P and P, so that the fore ship portion SA issupported by the latter two unit pontoons P and P only.

Subsequently, the separated unit pontoons P P and P, are suitablypositioned right beneath the fore ship portion SF after which theballast water in the float chambers of the unit pontoons P P and P aredischarged therefrom to float and expose the fore ship portion SF on thewater surface.

Under these conditions, both portions SF and SA are drawn close to eachother and jointed by welding to complete the hull S.

In this embodiment, five unit pontoons are used in such a manner thatthree unit pontoons are arranged for the fore ship portion SF and twounit pontoons for the aft ship portion SA because of which there occursan imbalance of buoyancy of both ship portions in certain instances.Therefore, in such cases, as shown in FIG. 10, it is also possible tocarry out the jointing operation iwth the hull S being somewhatinclined.

FIG. 11 embodiment provides a tubular means for communicating betweenone float chamber to another. For example, unit pontoon P is provided oneach of the respective sidewlls with a slidably mounted tubular member Twhich is adapted to be either inserted in a cavity passage of pontoon Pas shown in dotted lines or to be extended outwardly beyond the sidewallas shown in solid lines. Likewise, a tubular member T, which has aslightly less cross-sectional area than that of tubular member T isconstructed on unit pontoon P Thereby, the tubular members of therespective pontoon units may be interconnected in a telescopical manneror the like to provide a passageway for water to flow from one floatchamber to another. It is to be understood that suitable closure meansas illustrated by closure C are constructed on the unit pontoon toachieve an independent hermetically sealed unit when tubular member T ispositioned within the cavity passage or in the extended position.

Further, the respective tubular members in their extended positions alsoprovide a means to secure or fasten one unit to another in a spacedrelationship to achieve'the spaced position of the unit pontoon shown inFIG. 10. Further, the tubular members provide a stabilized and balancingeffect to the pontoon structure to enable the inclined position of thepontoon units in FIG. 10 to be achieved in a more efficient manner.

It is to be understood that various structural arrangements may be madeand still be within the scope of the disclosed FIG. 11 embodiment. Forexample, it is obvious that the amount of buoyant support can beincreased or decreased by adding or subtracitng pontoon units or modulesto or from the longitudinal line of units.

As has been described hereinbefore, with reference to the threeembodiments of the present invention, the application of this apparatusand method are not limited to the construction of ships or marinevessels but it can be extensively applied to the construction of marinefloat structures, for example, such as transport barges, floating docksand other marine structures.

In brief, the present invention is intended to provide apparatus and amethod of manufacturing marine float structures, comprising constructinglarge-sized marine float structures in suitably divided form on ahorizontal ship building base and using composite pontoons consisting ofmany upand down or forwardly and/or backwardly separable portions,wherein firstly, the first divided portion of the structure istransported onto the water surface, then said composite pontoon iscaused to sink down in the water to permit the floating of said firstdivided portion of the structure of its own accord on the water surface,successively, the second divided portion of the structure is alsotransported onto the water surface using the same pontoon, a part ofsaid pontoon is separated from the whole body and caused to sink down inthe water, said second divided portion of the structure is held on thewater surface using the remaining part of the pontoon and at the sametime, the firstly separated part of the pontoon is used to float saidfirst divided portion of the structure on the water surface and tosupport it thereon and finally, both divided portions of the structureare drawn close to each other so that they can be jointed together onthe water.

According to the present invention, the following advantages will beanticipated.

a. It is possible to construct large-sized float structures such asmarine vessels without using an inclined ship building base or shipbuilding dock so that various technical and economical problems involvedin the use of an inclined ship building base or dock can be extensivelysolved in a satisfactory manner.

b. As compared with the conventional methods of ship launching, whichhave heretofore been proposed using pontoons, the present inventionmakes it easily possible to construct structures of almost the samesizes as conventional structures using pontoons of about half size ofalso conventional pontoons, thereby proving the apparatus and the methodof the present invention to be considerably reasonable and economical.

. After the structure has been constructed in suitably sized and dividedform on an almost horizontal ship building base, each portion isseparately transferred onto the pontoon for mounting thereon. Thus, theoperation of transferring portions of the structures onto the pontoon isrendered very easy.

What we claim is:

l. A method of ship building for constructing largesized shipstructures, comprising the following steps:

the first step includes providing at least a first ship portion and asecond ship portion for constructing a ship on a ship building base,said ship builidng base being mounted on a dry-land type foundation;

the second step includes constructing the ship portions and transportingsaid first constructed ship portion onto a water surface using acomposite pontoon as a support thereof, thereafter said compositepontoon being sunk so as to float said first portion on the watersurface by its own buoyancy without the aid of the composite pontoon,said composite pontoon being constructed with a plurality ofindividually detachable unit pontoons longitudinally arranged in aspaced relationship to each other to form a forward and backwardlongitudinal line of pontoons for supporting the ship portions, theheight of said composite pontoon being made sufficient to compensate forthe intervening height difference between the level of the water surfaceand the level of the ship building base whenever either one of the shipportions is drawn from said foundation onto the water surface, and

each of said unit pontoons of said composite pontoon having a sufficientbuoyancy ofits own to hold each of said ship portions with positivebuoyancy supported beneath; the third step includes transporting saidsecond constructed ship portion onto the water surface using saidcomposite pontoon as the support thereof, said composite pontoon heldfloating on the water surface by virtue of the remaining second one ofunit pontoons after the composite pontoon is separated into the firstand second ones of unit pontoons and also after the first detached oneof the unit pontoons being sunk so as to regain its own buoyancy;

the fourth step includes said first buoyant constructed ship portionbeing supported in a floating state on the water surface with the aid ofsaid first sunken one of the unit pontoons after regaining its ownpositive buoyancy, and

the fifth step includes both first and second floated ship portions withthe aid of both first and second unit pontoons respectively being drawnto each other and welded together so as to unify them into a single shipunit while being held on the water surface.

2. A method of ship building according to claim 1, and further providinga water flow connection between respective spaced unit pontoons whereineach of the individually detachable unit pontoons includes an extendibletubular member for effecting a connection with an adjacent unit pontoonwhereby each formed unitary pontoon structure of individual unitpontoons is adapted to be inclined with respect to the water surface.

3. A method of ship building according to claim 1, further comprisingthe step of providing each of said unit pontoons with an extendibletubular member mounted thereon for effecting a water connection with anadjacent unit pontoon to form a unitary pontoon structure of individualunit pontoons whereby said unitary pontoon structure may be inclinedwith respect to the water surface.

1. A method of ship building for constructing large-sized shipstructures, comprising the following steps: the first step includesproviding at least a first ship portion and a second ship portion forconstructing a ship on a ship building base, said ship builidng basebeing mounted on a dryland type foundation; the second step includesconstructing the ship portions and transporting said first constructedship portion onto a water surface using a composite pontoon as a supportthereof, thereafter said composite pontoon being sunk so as to floatsaid first portion on the water surface by its oWn buoyancy without theaid of the composite pontoon, said composite pontoon being constructedwith a plurality of individually detachable unit pontoons longitudinallyarranged in a spaced relationship to each other to form a forward andbackward longitudinal line of pontoons for supporting the ship portions,the height of said composite pontoon being made sufficient to compensatefor the intervening height difference between the level of the watersurface and the level of the ship building base whenever either one ofthe ship portions is drawn from said foundation onto the water surface,and each of said unit pontoons of said composite pontoon having asufficient buoyancy of its own to hold each of said ship portions withpositive buoyancy supported beneath; the third step includestransporting said second constructed ship portion onto the water surfaceusing said composite pontoon as the support thereof, said compositepontoon held floating on the water surface by virtue of the remainingsecond one of unit pontoons after the composite pontoon is separatedinto the first and second ones of unit pontoons and also after the firstdetached one of the unit pontoons being sunk so as to regain its ownbuoyancy; the fourth step includes said first buoyant constructed shipportion being supported in a floating state on the water surface withthe aid of said first sunken one of the unit pontoons after regainingits own positive buoyancy, and the fifth step includes both first andsecond floated ship portions with the aid of both first and second unitpontoons respectively being drawn to each other and welded together soas to unify them into a single ship unit while being held on the watersurface.
 2. A method of ship building according to claim 1, and furtherproviding a water flow connection between respective spaced unitpontoons wherein each of the individually detachable unit pontoonsincludes an extendible tubular member for effecting a connection with anadjacent unit pontoon whereby each formed unitary pontoon structure ofindividual unit pontoons is adapted to be inclined with respect to thewater surface.
 3. A method of ship building according to claim 1,further comprising the step of providing each of said unit pontoons withan extendible tubular member mounted thereon for effecting a waterconnection with an adjacent unit pontoon to form a unitary pontoonstructure of individual unit pontoons whereby said unitary pontoonstructure may be inclined with respect to the water surface.